Sprayers, such as broadcast sprayers are used across an array of applications, including farms, golf courses and residential properties, to apply water or other liquids, such as pesticides including herbicides, insecticides and the like. As such, these sprayers may need to cover a large area and, therefore, generally include large tanks strapped to a vehicle, such as an all-terrain vehicle (ATV) or golf cart, or may be mounted onto a tow-behind trailer. Typically in use, these tanks are filled with a selected fluid composition that is to be applied. By way of example, pesticide solutions may be anywhere from about 1% to about 10% active chemical in water. In one scenario, a user may spray a diluted herbicide solution, such as to target thistle. However, to apply a second pesticide solution, such as a diluted insecticide to fruit trees, the user will first have to completely empty the tank of the herbicide solution before rinsing the tank of any residual chemicals and finally refilling the tank with the desired insecticide solution. As may be readily apparent from the above, there are numerous drawbacks to such systems. For example and without limitation, such drawbacks may include waste of chemicals, the need for controlled disposal of unused chemicals, the time consuming need to thoroughly clean the tank between applications and the potential for cross-contamination and application of unwanted chemicals after incomplete or unsuccessful cleaning of the tank.
To alleviate some of the above-referenced drawbacks of broadcast sprayers, systems have been developed which segregate the chemical portion from the water/diluent portion of the system. In such systems, the chemical is stored in a smaller, separate tank than the large water tank. Metering devices may then add chemical to a flow of water prior to emission from a wand or boom sprayer. In this manner, the chemical remains isolated from the water tank, thereby minimizing or avoiding possible contamination of the water source. However, heretofore systems require complex plumbing regimes and interconnectivities of the various components making such systems difficult to use and burdensome to operate and clean.
Broadcast sprayers have also been configured as variable pressure sprayers which may selectively spray fluid from either a spray wand or through a boom-and-nozzle arrangement where multiple nozzles may be supported on a boom. Due to the multiple nozzles within the boom-and-nozzle arrangement, fluid must be delivered at high pressure so as to enable proper spraying at each of the individual nozzles. However, a spray wand uses a single nozzle and may become damaged if it receives high pressure fluid. To that end, current systems typically use pumps with a high pressure cut out switch. These systems are configured with a recirculation manifold whereby excess flow from the pump is diverted back to the supply tank. A valve and pressure gauge is provided on the manifold so the user can tune the percentage of flow going back to the tank while maintaining adequate pressure for the lower flow application (spray wand). Without providing for this recirculation pressure bleed off in the low flow application, pressure would build quickly and rapidly cycle the pressure cut off switch. A situation that is detrimental to both the switch and the pump. However, such a system should not be used in two-tank systems as the mixed fluid exiting the pump would be recycled to the water tank, thereby contaminating the water tank and changing the concentration of the chemical that is being sprayed.
Thus, there remains a need for a sprayer that segregates the chemical tank from the water tank but is also more easily plumbed, operated and cleaned. There remains a further need for a variable pressure sprayer wherein the mixed fluid is not recycled to the diluent tank when operating at reduced spraying pressure. The present invention satisfies this as well as other needs.